High expansion sealing glass and composite article



United States Patent 3,449,203 HIGH EXPANSION SEALING GLASS ANDCOMPOSITE ARTICLE Hellmuth G. Fischer, Toledo, Ohio, assignor to Owens-Illinois, Inc., a corporation of Ohio No Drawing. Filed Aug. 24, 1966,Ser. No. 574,543 Int. Cl. B32b 17/06, 15/20; C03c 3/04 US. Cl. 161-49611 Claims The prevent invention relates to novel glass compositions.More particularly, the instant invention pertains to novel glasscompositions possessing a high coeflicient of thermal expansion andimproved chemically durability against aqueous media. In another aspect,the invention relates to vitreous sealing glasses for effectingglass-tometal seals or glass-to-glass seals.

A critical need exists for sealing glass with a high coefiicient ofthermal expansion for bonding preformed parts, wherein said assembledparts consist of glass-toglass and glass-to-metal; such metal includingcopper or copper containing alloys. Historically, the alkali oxides,especially sodium oxide and potassium oxide, are em.- ployed to increasethe coeflicient of thermal expansion of glasses; however, as theconcentration of these alkali oxides is increased, there is anaccompanying tendency towards devitrification and a decrease in thechemical durability of the glass against aqueous attack. Attempts havebeen made by the prior art to avoid the high tendency towarddevitrification associated with the increased alkali concentration bythe use of alumina and calcium oxide, but these attempts have not led tosatisfactory results. Likewise, the employment of the oxides ofmagnesium, zinc, and barium have been unsatisfactory as the tendencytowards devitrification occurs during the working and forming stages ofthe glass. It will be appreciated by those versed in the art that if aglass composition can be formulated possessing a high coeflicient ofthermal expansion and with a decreased tendency towards devitrification,said glass would represent a substantial contribution to the art.Likewise, it will be further appreciated by those skilled in the artthat a glass with good sealing properties for copper or copper alloys,and with good working properties would have a positive commercial valueand would also increase the usefulness of said glass.

Accordingly, it is an object of the present invention to provide novelglass compositions.

It is a further object of this invention to provide glass compositionshaving a high coelficient of thermal expansion.

Yet a further object of this invention is to provide glass compositionsfor sealing glass-to-copper and copper alloys.

A still further object of this invention is to provide glasscompositions with an improved resistance against aqueous attack and adecreased degree of devitrification.

Yet a still further object of the present invention is to provide aglass composition with a higher softening point.

These and other objects of this invention will become apparent from thefollowing detailed description and claims.

In attaining the objects and features of the present invention, it hasnow been discovered that glass compositions with a linear coefiicient ofthermal expansion of about 150 to 180x l0"/ C. (0-300 C.) can be madeice by intimately blending silica, fluorine, zirconium, the oxides ofmagnesium, zinc and barium, the alkali oxides and other glass formingingredients in inventive amounts. The glass compositions of the instantinvention contain the following components: 40' to 50 weight per centSiO 3 to 9 weight percent MgO, 2 to 7 weight percent BaO, about 0 to 5weight percent ZrO about 3 to 8 weight percent A1 0 about 2 to 7 weightpercent ZnO, about 0 to 2 weight percent CaO, about 25 to 28 weightpercent Na O, about 5 to 9 weight percent K 0, about 0 to 4 weightpercent B 0 and about 1.5 to 5.5 Weight percent fluoride.

A now preferred group of glasses for sealing to copper and metals ofsimilar high expansion comprises glasses having a coefficient of thermalexpansion (0300* C.) from 150 to 1 10- C. and which contain 40 to 45weight percent SiO 4 to 6 weight percent MgO, 2 to 3 weight percent BaO,1 to 2 weight percent ZrO 0.1 to 1 weight percent CaO, 4 to 5 weightpercent A1 0 2 to 4 weight percent ZnO, 7 to 8 weight percent K 0, 25 to28 weight percent Na O, 1 to 2 weight percent B 0 and 2 to 3 weightpercent F a total of 44 to 50 weight percent SiO +Al O a Na O to K 0ratio of 1:1 to 6:1 and a total of 8 to 12 weight percent Al O +ZnO+BaO.Exemplary of other glass compositions are a glass consisting essentiallyof 42 to 44 weight percent SiO;;, 5 to 6 weight percent MgO, 2 to 3weight percent BaO, l to 2 weight percent ZrO 4 to 5 weight percent A1 03 to 4 weight percent ZnO, 0:1 to 0.5 weight percent CaO, 7 to 8 weightpercent K 0, 26 to 27 weight percent Na O, 1 to 2 weight percent B 0 and2 to 3 weight percent fluorine; and a glass consisting essentially of 42to 44 weight percent SiO 5 to 6 weight percent MgO, 2 to 3 weightpercent BaO, 5 to 7 weight percent ZrO 3 to 4 weight percent ZnO, 0.1 to0.5 weight percent CaO, 7 to 8 weight percent K 0, 26 to 27 weightpercent Na O, 1 to 2 weight percent B 0 and 2 to 3 weight percentfluorine.

In the above disclosed glass compositions, the addition offluorine-containing compounds, for example alkali fluoride, alkalisilico-fluoride, sodium fluoride, aluminum fluoride, cryolite, fluorsparand the like resulting in amounts up to 5.5 weight percent of fluorinehas been found to unexpectedly make possible the employment of increasedlimits of alumina and the oxides of magnesium, zinc and barium withoutcausing an increased tendency toward uncontrolled devitrification. Thepresence of fluorine in the glass composition, in addition, makespossible an alkali oxide, Na O and K 0, concentration of about 33 to 38weight percent with a ratio of Na O to K 0 of from 1:1 to 621 withoutproducing devitrification.

The chemical durability or resistance of the novel glasses of theinvention against water is further improved and the softening point israised by the addition of zirconium oxide in weight percent ranges of upto 5%. The presence of zirconium oxide in the glass was unexpectedlymade without causing a tendency toward devitrification, and the glasscould be formed and reheated in a blast flame without any visibleevidence of the above tendency.

The above and following description and examples are merelyrepresentative of the mode and mannerof the invention and are not to beconstrued as limiting the invention, as these and other methods will beobvious from the instant disclosure to those skilled in the art.

3 EXAMPLE 1 A novel glass composition was prepared from the followingbatch components:

Components Weight in grams Sand 44.5 Magnesium oxide 6 Barium carbonate3.8 Zirconium oxide 1.5 Aluminum hydroxide 5.9

I Zinc oxide 3.5 Fluorspar 0.35 Soda ash 43.6 Sodium fluoride 0.4 Potash12.3 Boric acid 3.5 Cryolite 4.5 Sodium nitrate 0.6 Sodium sulfate(anhydrous) 0.3 Arsenic (AS203) 0.1

Sodium selenite 0.002

The above batch materials were intimately blended and melted in a 90%platinum-% rhodium crucible for 3 to 5 hours, at 1300 to 1350 C. and inan air atmosphere. The melting was carried out in an electrically heatedfurnace, although, other heat sources can :be successfully employed.

The novel glass prepared from the above melt had the following weightpercent composition:

Components Weight percen SiO 42.6 MgO 5.74 BaO 2.84 Zr0 1.44

A1 0 4.71 ZnO 3.30 CaO 0.24 K 0 7.90 Na O 26.71 B 0 1.89

This glass has a coefficie'nt of thermal expansion of about 175 10- C.between 20 and 400 C. and a softening point of about 510 C.

The chemical resistance for the above glass was measured by the standardgrain test, and compared against similar glass compositions forresistance against water attack. The conventional standard grain testconsists essentially of crushing a ten gram sample of the glass to betested into a particle size of about 0.3 to 0.5 mm. diameter, placingthe grains of glass thus obtained in a chemically resistant flaskequipped with a reflux condenser and refluxing the grains of glass in100 ml. of distilled water for 4 hours at boiling temperature. Thequantity of dissolved substance is then determined by vaporizing ameasured quantity of the employed water, drying the residue in an ovenand weighing the resulting product. The result obtained for the glass ofExample 1 was 200 mg. The results for two glass compositions essentiallyfree of fluorine and zirconium and consisting essentially of, expressedin weight percent, 44.25% SiO 6.0% MgO, 3.0% BaO, 5.0% A1 0 3.5% ZnO,0.25% CaO, 8.5% K 0, 27.5% Na O, and 2.0% B 0 and a glass consistingessentially of 43.9% SiO 5.95% MgO, 2.9% BaO, 4.96% A1 0 3.5% ZnO, 0.25%CaO, 8.4% K 0, 28.1% Na O, and 1.98% B 0 were respectively 734 and 1167mgs. The unobvious and unexpected increased chemical durability for thenovel subject glasses appears to be demonstrated by a decreased loss ofweight by addition of fluorine and Zirconium to the subject glasses.

4- EXAMPlLEZ Components Weight in grams Sand (99.8% SiO 2225 Magnesiumoxide 300 Barium carbonate 190 Aluminum hydroxide (65.4% A1 0 471 Zincoxide 175 Calcium fluoride 18 Sodium carbonate 2180 Sodium fluoridePotassum carbonate 6 1;,5 Boric acid Aluminum fluoride"; .r.. '90 Sodiumnitrate -2 Y 30 Sodium sulphate (anhydrous) ;i 1. 15 Arsenic (As O 5 Theabove-listed batch componentsv we re ,intima tely blended to obtain asubstantially homogeneous mixture and then the mixture was melted in a90% platinum 10% rhodium cruc'iblein an electrically heated furnace for2 hours and 20 minutes at 23 80. to 2470" F., and.in an air atmosphere.I

The novel glass preparedfrorn the above melt had, the followingtheoretically calculated composition:

Weight percent Components- SiO 42.6 MgO .1 5.74 BaO 2.85 A1 0 6.15 ZnO3.30 CaO 0.24 K 0 -2 7.90 Na O 26.71. B 0 189 F 2.58

The glass had a coefiicient of expansion of 153x10 (0-300 C.), anannealed density of 2.6364, a softening point temperature of 502 C., andan annealing point of EXAMPLE 3 A novel sealing glass compositionsimilar to the glass composition set forth in Example 2, wherein theinstant,

glass contained both fluorine and zirconium, was prepared.

from the following batch ingredients:

Weightin grams The above ingredients were thoroughlymixed to obtain awell-blended homogeneous mixture and the mixture was melted in a90%"platinum-10% rhodium crucible in an' electrically heated furnace at2380 to 2450" F., for 2 hours and 45 minutes, and in an air atmosphere.

The novel glass prepared from the above melt had the followingtheoretically calculated composition:

The glass thus prepared possessed the following physicalcharacteristics: a coefiicient of thermal expansion of 1519x10 (-300C.), an annealing point of 370 C., a strain point of 354 C., and anunannealed density of 2.6697.

The glass compositions of Example 2 and Example 3 were tested for theirresistance against aqueous attack by a standard powdered glass test. Inthis test, glass samples were crushed in a mortar to a fine grain size.The grains which pass through a No. 40 sieve (420 micron) and retainedon a No. 50 sieve (297 micron) were used for test purposes. The crushedgrains were exposed to 50 ml. of distilled water at 121 C. for 30minutes in a conventional autoclave. The resulting extract solution wastitrated to the methyl red end point with 0.02 N H SO and the volume ofacid used for titration was recorded. The results obtained for twoglasses prepared according to Example 2, that were essentially-free ofzirconium, were 251.0 and 250.7 ml. of 0.02 H SO The results obtainedfor two glass compositions, prepared according to Example 3 thatcontained zirconium and fluorine, were 221.2 and 225.3 ml. of 0.02 N H80 This test data is seen to illustrate the unexpected and improvedchemical durability against aqueous attack for the subject glasses.

The glass compositions of the instant invention can be used as vitreoussealing glasses for assembling preformed parts. That is, the vitreoussealing glasses can be used for effecting seals, such as glass-to-glass,glass-to-metal or the like. The sealing glasses can be applied by boththe conventional hot or cold techniques. If the cold procedure isutilized, the sealing glass is ground and mixed with a suitable carrieror vehicle to form a paste-like mixture. One acceptable vehicle iscomposed of about 1 to 3%, usually about 1 to 2% nitrocellulose in amylacetate. Other acceptable organic binders or vehicles can beemployed'provided they will not adversely affect the sealing glass andprovided they readily burn off and violatize during the heatingprocedure of the sealing of the preformed parts. As an example of otherorganic binders that can be used are gelatine dissolved in water,nitrocellulose and butyl acetate, camphor with cellulose and the like.

The vitreous sealing glass can be applied by using art acceptedtechniques, such as spatula, extrusion, cold dip, brush, doctor blade orany like means. The sealing glass can also be used in bead form and thesealing carried out in a gas-oxygen flame or any suitable flame.Alternatively, at least one of the surfaces to be sealed can be coatedwith the sealing glasses, the parts assembled, dried and sealed in anoven, and finally cooled to room temperature.

A vitreous sealing glass consisting essentially of 42.6 weight percentSiO' 5 .74 weight percent MgO', 2.84 weight percent BaO, 2.84 weightpercent A1 0 3.30 Weight percent ZnO, 024 Weight percent CaO, 7.9-0weight percent K 0, 26.71 weight percent Na O, 1.89 weight percent B 0and 2.58 Weight percent F was drawn into a cane of about inch diameterand bead sealed to a piece of copper. The stress for this seal was 2100p.s.i. compression. A second bead seal with a compression of 1200 p.s.i.was effected by sealing a composition consisting essentially of 42.65weight percent SiO 1.44 weight percent ZrO 5 .74 weight percent MgO,2.84 weight percent BaO, 4.71

weight percent A1 0 3.30 weight percent ZnO, 0.24 weight percent CaO,7.90 weight percent K 0, 26.71 weight percent Na O, 1.89 weight percentB 0 and 2.58 weight percent F to a given length of copper. Samples ofthe composition described in Example 1 were sealed to copper, either inthe form of wires or to plates where the glass was glazed to the platesurface and these seals were kept under observation for a period ofseveral months with no apparent visible evidence of cracking or otherkinds of deterioration observed.

The glass compositions of the present invention have a high thermalcoefiicient of expansion and are therefore of import to commerce andscience. The sealing glasses can be used for sealing copper wires intoglass surfaces as required in the manufacture of electronic components,such as diodes and the like. The glasses of the instant invention canalso be used for insulating copper coils, for example, coils intransformers, voltage regulators and the like.

As generally understood by those versed in the art glasses are commonlyanalyzed for the metals, and the composition is reported on the basis ofthe theoretically calculated normal oxide of each cation so analyzed.However, when fluorine is present, it is actually present as a fluorideof one or more of the cations in the glass or similarly bound in theglass structure, but it is analyzed separately and reported as fluorine.Actually, of course, the fluorine replaces part of the oxygen in theoxides of the composition. Hence, although the sealing glasses ofpresent invention contain cations which may be present in the glasses asoxides and or fluorides, such cations are expressed on a theoreticallycalculated oxide basis in weight percent. Of course it should beunderstood that the amount of combined oxygen actually present in theglass is less than that so expressed in the foregoing oxide basis by anamount chemically equivalent to the fluorine present in the glass.

I claim:

1. A vitreous sealing glass composition wherein said compositionconsists essentially of 40 to 50 weight percent SiO 3 to 9 weightpercent MgO, 2 to 7 weight percent BaO, 0 to 5 weight percent Z10 3 to 8weight percent A1 0 2 to 7 weight percent ZnO, 0 to 2 weight percentCaO, 25 to 28 weight percent Na O, 5 to 9 weight percent K O, 0 to 4Weight percent B 0 and 1.5 to 5.5 weight percent F 2. The glasscomposition according to claim 1 wherein the concentration of Na O plusK 0 is 33 to 38 weight percent.

3. The glass composition according to claim 1 wherein the ratio of Na Oto K 0 is 1:1 to 6:1.

4. The glass composition according to claim 1 wherein said glassconsists essentially of 42 to 44 weight percent SiO-,,, 5 to 6 weightpercent MgO, 2 to 3 weight percent BaO, 1 to '2 weight percent ZrO-,,, 4to 5 weight percent A1 0 3 to 4 weight percent ZnO, 0.1 to 0.5 weightpercent CaO, 7 to 8 weight percent K 0, 26 to 27 weight percent Na O, 1to 2 weight percent B 0 and 2 to 3 weight percent F 5. The glasscomposition according to claim 1 wherein said glass consists essentiallyof 42 to 44 weight percent SiO 4 to 6 weight percent MgO, 2 to 3 weightpercent BaO, 1 to 2 weight percent ZrO 0 to 1 weight percent CaO, 4 to 5weight percent A1 0 2 to 4 weight percent ZnO, 7 to 8 weight percent K0, 25 to 2'8 weight percent Na O, 1 to 2 weight percent B 0 and 2 to 3weight percent F 6. The glass composition according to claim 1 whereinsaid glass has a total of 8 to 24 weight percent MgO+Al O +ZnO, and atotal of 7 to 22 weight percent A1zO3+ZI10+Ba0.

7. A glass composition according to claim 1 wherein said glass consistsessentially of 40 to 50 weight percent SiO 4 to 6 weight percent MgO, 2to 3 weight percent B20, '1 to 2 weight percent ZrO to 1 weight percentCaO, 4 to weigh't'percent A1 0 2 to 4 weight percent ZnO, 7 'to- 8weight percent K 0, 25 to 28 weight percent Na O, 1 to 2 weight percentB 0 and 2 to 3 weight F 8. The glass according to claim 7 wherein saidglass has a total of 44 to 55 weight percent SiO +Al O and a total of 8to 12 weight percent Al O +ZnO+BaO, anda total of 1 0 to 15 weightpercent MgO+Al O +ZnO.

9. The glass composition according to claim 1 wherein said glassconsists essentially of 42.6 weight percent SiO 5.7 weight percent MgO,2.8 weight percent BaO, 1.4 weight percent ZrO 4.7 weight percent A1 03,3.3 weight percent ZnO, 0.2 weight percent CaO, 7.9 weight percent K 0,26.7 weight percent Na O, 1.9 Weight percent B 0 and 2.6 Weight percentF '10. A composite article comprising preformed parts, at least one ofwhich parts is a metal and a layer of a vitreous sealing glass betweensaid parts and integrally bonded thereto and wherein said solder glassconsist essentially of to 45 weight percent SiO 4 to 6 weight percentMgO, 2 to 3 Weight percent BaO, 1 to 2 weight percent-ZrO 4 to 5 weightpercent A1 0 2to4 weight-percent ZnO, 0.1 to 0.5 weight'percentCaO, 25to 28 weight percent'Na O,

to 2 weight percent B 0 v- 11. An article. according to claim 10 whereinsaid-metal is copper. M r it References Cited UNITED STATES PATENTS2,844,693; Ti/g Rigterink r.f 106 48 XR 2, 29,727 3/19 9 Oldfield et 1.V 1Q6'52 2,933,458 4/1960 King et a1. 1()652 3,240,661.3-3/1966-Babcock- 161196 HELEN MfMcCARTHYQPrimary Examiner I f U.'s,c 1'."X.R.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,449,203 June 10 1969 Hellmuth G. Fischer It is certified that error appearsin the above identified patent and that said Letters Patent are herebycorrected as shown below:

Column 1, line 10, "prevent" should read present Column 3, line 18,"Cryolite" should read Cryolithe Column 6, line 63, "4" should read Sline 64, "l to 2 weight percent ZrO should be canceled; line 64 "0"should read 0.1 line 64, "1" should read 0.5 line 65, "4", firstoccurrence, should read S line 65, "5" should read 7 line 65, "2" shouldread 3 line 66, "25" should read 26 line 66, "28" should read 27 Column7, line 19, "consist" should read consists Signed and sealed this 2ndday of June 1970. (SEAL) Attest:

Edward M. Fletcher, J r.

Attesting Officer Commissioner of Patents WILLIAM E. SCHUYLER, JR.

10. A COMPOSITE ARTICLE COMPRISING PREFORMED PARTS, AT LEAST ONE OF WHICH PARTS IS A METAL AND A LAYER OF A VITREOUS SEALING GLASS BETWEEN SAID PARTS AND INTEGRALLY BONDED THERETO AND WHEREIN SAID SOLDER GLASS CONSIST ESSENTIALLY OF 40 TO 45 WEIGHT PERCENT SIO2 4 TO 6 WEIGHT PERCENT MGO, 2 TO 3 WEIGHT PERCENT BAO, 1 TO 2 WEIGHT PERCENT ZRO2, 4 TO 5 WEIGHT PERCENT AL2O3, 2 TO 4 WEIHT PERCENT ZNO,0.1 TO 0.5 WEIGHT PERCENT CAO, 25 TO 28 WEIGHT PERCENT NA2O, 7 TO 8 WEIGHT PERCENT K2O, 2 TO 3 WEIGHT PERCENT F2 AND 1 TO 2 WEIGHT PERCENT B2O3. 